Building Semipermeable Films One Monomer at a Time: Structural Advantages via Molecular Layer Deposition vs Interfacial Polymerization.

Molecular layer deposition (MLD) provides the opportunity to perform condensation polymerization one vaporized monomer at a time for the creation of precise, selective nanofilms for desalination membranes. Here, we compare the structure, chemistry, and morphology of two types of commercial interfacial polymerzation (IP) membranes with lab-made MLD films. M-phenylenediamine (MPD) and trimesoyl chloride (TMC) produced a cross-linked, aromatic polyamide often used in reverse osmosis membranes at MLD growth rates of 2.

Area-Selective Atomic Layer Deposition of ZnO on Si\SiO Modified with Tris(dimethylamino)methylsilane.

Delayed atomic layer deposition (ALD) of ZnO, i.e., area selective (AS)-ALD, was successfully achieved on silicon wafers (Si\SiO) terminated with tris(dimethylamino)methylsilane (TDMAMS).

Mechanisms of Thermal Atomic Layer Etching.

ConspectusAtomic layer control of semiconductor processing is needed as critical dimensions are progressively reduced below the 10 nm scale. Atomic layer deposition (ALD) methods are meeting this challenge and produce conformal thin film growth on high aspect ratio features. Atomic layer etching (ALE) techniques are also required that can remove material with atomic layer precision.

Probing the Atomic-Scale Structure of Amorphous Aluminum Oxide Grown by Atomic Layer Deposition.

Atomic layer deposition (ALD) is a well-established technique for depositing nanoscale coatings with pristine control of film thickness and composition. The trimethylaluminum (TMA) and water (HO) ALD chemistry is inarguably the most widely used and yet to date, we have little information about the atomic-scale structure of the amorphous aluminum oxide (AlO) formed by this chemistry. This lack of understanding hinders our ability to establish process-structure-property relationships and ultimately limits technological advancements employing AlO made ALD.

In Situ Thermal Atomic Layer Etching for Sub-5 nm InGaAs Multigate MOSFETs.

Thermal atomic layer etching (ALE) was demonstrated on ternary III-V compound semiconductors. In particular, thermal ALE on InGaAs and InAlAs was achieved with sequential, self-limiting fluorination and ligand-exchange reactions using hydrogen fluoride (HF) as the fluorination reactant and dimethylaluminum chloride (DMAC) as the ligand-exchange reactant. Thermal ALE was investigated on planar surfaces and three-dimensional nanostructures.

Electron-Enhanced Atomic Layer Deposition of Boron Nitride Thin Films at Room Temperature and 100 °C.

Electron-enhanced atomic layer deposition (EE-ALD) was used to deposit boron nitride (BN) thin films at room temperature and 100 °C using sequential exposures of borazine (BNH) and electrons. Electron-stimulated desorption (ESD) of hydrogen surface species and the corresponding creation of reactive dangling bonds are believed to facilitate borazine adsorption and reduce the temperature required for BN film deposition. In situ ellipsometry measurements showed that the BN film thickness increased linearly versus the number of EE-ALD cycles at room temperature.

WO and W Thermal Atomic Layer Etching Using "Conversion-Fluorination" and "Oxidation-Conversion-Fluorination" Mechanisms.

The thermal atomic layer etching (ALE) of WO and W was demonstrated with new "conversion-fluorination" and "oxidation-conversion-fluorination" etching mechanisms. Both of these mechanisms are based on sequential, self-limiting reactions. WO ALE was achieved by a "conversion-fluorination" mechanism using an AB exposure sequence with boron trichloride (BCl) and hydrogen fluoride (HF).

Surface modification of acetaminophen particles by atomic layer deposition.

Active pharmaceutical ingredients (APIs) are predominantly organic solid powders. Due to their bulk properties many APIs require processing to improve pharmaceutical formulation and manufacturing in the preparation for various drug dosage forms. Improved powder flow and protection of the APIs are often anticipated characteristics in pharmaceutical manufacturing.

Coating Solution for High-Voltage Cathode: AlF Atomic Layer Deposition for Freestanding LiCoO Electrodes with High Energy Density and Excellent Flexibility.

Freestanding LiCoO/multiwall carbon nanotube/nanocellulose fibril (LCO-MWCNT-NCF) electrodes are fabricated by a vacuum filtration technique. The electrode has a high LCO loading of 20 mg/cm with excellent flexibility, uniform material distribution, and low surface resistivity. When coated with 2 ALD cycles of AlF, LCO-MWCNT-NCF has a high specific capacity of 216 mAh/g at 4.

Thermal Atomic Layer Etching of SiO by a "Conversion-Etch" Mechanism Using Sequential Reactions of Trimethylaluminum and Hydrogen Fluoride.

The thermal atomic layer etching (ALE) of SiO was performed using sequential reactions of trimethylaluminum (TMA) and hydrogen fluoride (HF) at 300 °C. Ex situ X-ray reflectivity (XRR) measurements revealed that the etch rate during SiO ALE was dependent on reactant pressure. SiO etch rates of 0.

Competition between AlO atomic layer etching and AlF atomic layer deposition using sequential exposures of trimethylaluminum and hydrogen fluoride.

The thermal atomic layer etching (ALE) of AlO can be performed using sequential and self-limiting reactions with trimethylaluminum (TMA) and hydrogen fluoride (HF) as the reactants. The atomic layer deposition (ALD) of AlF can also be accomplished using the same reactants. This paper examined the competition between AlO ALE and AlF ALD using in situ Fourier transform infrared (FTIR) vibrational spectroscopy measurements on AlO ALD-coated SiO nanoparticles.

Rapid Growth of Crystalline Mn5O8 by Self-Limited Multilayer Deposition using Mn(EtCp)2 and O3.

This work investigates the use of ozone as a post-treatment of ALD-grown MnO and as a coreactant with bis(ethylcyclopentadienyl)manganese (Mn(EtCp)2) in ALD-like film growth. In situ quartz crystal microbalance measurements are used to monitor the mass changes during growth, which are coupled with ex situ materials characterization following deposition to evaluate the resulting film composition and structure. We determined that during O3 post-treatment of ALD-grown MnO, O3 oxidizes the near-surface region corresponding to a conversion of 22 Å of the MnO film to MnO2.

Prospects for Thermal Atomic Layer Etching Using Sequential, Self-Limiting Fluorination and Ligand-Exchange Reactions.

Thermal atomic layer etching (ALE) of Al2O3 and HfO2 using sequential, self-limiting fluorination and ligand-exchange reactions was recently demonstrated using HF and tin acetylacetonate (Sn(acac)2) as the reactants. This new thermal pathway for ALE represents the reverse of atomic layer deposition (ALD) and should lead to isotropic etching. Atomic layer deposition and ALE can together define the atomic layer growth and removal steps required for advanced semiconductor fabrication.

Electron Enhanced Growth of Crystalline Gallium Nitride Thin Films at Room Temperature and 100 °C Using Sequential Surface Reactions.

Low energy electrons may provide mechanisms to enhance thin film growth at low temperatures. As a proof of concept, this work demonstrated the deposition of gallium nitride (GaN) films over areas of ∼5 cm at room temperature and 100 °C using electrons with a low energy of 50 eV from an electron flood gun. The GaN films were deposited on Si(111) wafers using a cycle of reactions similar to the sequence employed for GaN atomic layer deposition (ALD).

Amorphous Ultrathin SnO2 Films by Atomic Layer Deposition on Graphene Network as Highly Stable Anodes for Lithium-Ion Batteries.

Amorphous SnO2 (a-SnO2) thin films were conformally coated onto the surface of reduced graphene oxide (G) using atomic layer deposition (ALD). The electrochemical characteristics of the a-SnO2/G nanocomposites were then determined using cyclic voltammetry and galvanostatic charge/discharge curves. Because the SnO2 ALD films were ultrathin and amorphous, the impact of the large volume expansion of SnO2 upon cycling was greatly reduced.

Electrical and thermal conduction in ultra-thin freestanding atomic layer deposited W nanobridges.

Work presented here measures and interprets the electrical and thermal conductivities of atomic layer deposited (ALD) free-standing single film and periodic tungsten and aluminum oxide nanobridges with thicknesses from ∼5-20 nm and ∼3-13 nm, respectively. Electrical conductivity of the W films is reduced by up to 99% from bulk, while thermal conductivity is reduced by up to 91%. Results indicate phonon contribution to thermal conductivity is dominant in these ALD films and may be substantially reduced by the incorporation of periodicity in the ALD W/Al2O3 nanolaminates.

Doped Si nanoparticles with conformal carbon coating and cyclized-polyacrylonitrile network as high-capacity and high-rate lithium-ion battery anodes.

Doped Si nanoparticles (SiNPs) with conformal carbon coating and cyclized-polyacrylonitrile (PAN) network displayed capacities of 3500 and 3000 mAh g(-1) at C/20 and C/10, respectively. At 1 C, the electrode preserves a specific discharge capacity of ∼1500 mAh g(-1) for at least 60 cycles without decay. Al2O3 atomic layer deposition (ALD) helps improve the initial Coulombic efficiency (CE) to 85%.

Structure and Reactivity of Alucone-Coated Films on Si and Li(x)Si(y) Surfaces.

Coating silicon particles with a suitable thin film has appeared as a possible solution to accommodate the swelling of silicon upon lithiation and its posterior cracking and pulverization during cycling of Li-ion batteries. In particular, aluminum alkoxide (alucone) films have been recently deposited over Si anodes, and the lithiation and electrochemical behavior of the system have been characterized. However, some questions remain regarding the lithium molecular migration mechanisms through the film and the electronic properties of the alucone film.

Growth and Characterization of Al2O3 Atomic Layer Deposition Films on sp(2)-Graphitic Carbon Substrates Using NO2/Trimethylaluminum Pretreatment.

The growth of Al2O3 films by atomic layer deposition (ALD) on model sp(2)-graphitic carbon substrates was evaluated following a nitrogen dioxide (NO2) and trimethylaluminum (TMA) pretreatment to deposit an Al2O3 adhesion layer. Al2O3 ALD using TMA and water (H2O) as the reactants was used to grow Al2O3 films on exfoliated highly ordered pyrolitic graphite (HOPG) at 150 °C with and without the pretreatment procedure consisting of five NO2/TMA cycles. The Al2O3 films on HOPG substrates were evaluated using spectroscopic ellipsometry and electrochemical analysis to determine film thickness and quality.

Surface-coating regulated lithiation kinetics and degradation in silicon nanowires for lithium ion battery.

Silicon (Si)-based materials hold promise as the next-generation anodes for high-energy lithium (Li)-ion batteries. Enormous research efforts have been undertaken to mitigate the chemo-mechanical failure due to the large volume changes of Si during lithiation and delithiation cycles. It has been found that nanostructured Si coated with carbon or other functional materials can lead to significantly improved cyclability.

Atomic layer etching of Al2O3 using sequential, self-limiting thermal reactions with Sn(acac)2 and hydrogen fluoride.

The atomic layer etching (ALE) of Al2O3 was demonstrated using sequential, self-limiting thermal reactions with tin(II) acetylacetonate (Sn(acac)2) and hydrogen fluoride (HF) as the reactants. The Al2O3 samples were Al2O3 atomic layer deposition (ALD) films grown using trimethylaluminum and H2O. The HF source was HF-pyridine.

In situ transmission electron microscopy probing of native oxide and artificial layers on silicon nanoparticles for lithium ion batteries.

Surface modification of silicon nanoparticles via molecular layer deposition (MLD) has been recently proved to be an effective way for dramatically enhancing the cyclic performance in lithium ion batteries. However, the fundamental mechanism of how this thin layer of coating functions is not known, which is complicated by the inevitable presence of native oxide of several nanometers on the silicon nanoparticle. Using in situ TEM, we probed in detail the structural and chemical evolution of both uncoated and coated silicon particles upon cyclic lithiation/delithation.

GaN nanowire coated with atomic layer deposition of tungsten: a probe for near-field scanning microwave microscopy.

GaN nanowires were coated with tungsten by means of atomic layer deposition. These structures were then adapted as probe tips for near-field scanning microwave microscopy. These probes displayed a capacitive resolution of ~0.

Growth and properties of hafnicone and HfO(2)/hafnicone nanolaminate and alloy films using molecular layer deposition techniques.

Molecular layer deposition (MLD) of the hafnium alkoxide polymer known as "hafnicone" was grown using sequential exposures of tetrakis(dimethylamido) hafnium (TDMAH) and ethylene glycol (EG) as the reactants. In situ quartz crystal microbalance (QCM) experiments demonstrated self-limiting reactions and linear growth versus the number of TDMAH/EG reaction cycles. Ex situ X-ray reflectivity (XRR) analysis confirmed linear growth and measured the density of the hafnicone films.

Amorphous vanadium oxide coating on graphene by atomic layer deposition for stable high energy lithium ion anodes.

Uniform amorphous vanadium oxide films were coated on graphene via atomic layer deposition and the nano-composite displays an exceptional capacity of ~900 mA h g(-1) at 200 mAg(-1) with an excellent capacity retention at 1 A g(-1) after 200 cycles. The capacity contribution (1161 mA h g(-1)) from vanadium oxide only almost reaches its theoretical value.